The Indiana State sentinel. [volume] (Indianapolis) 1868-1895, 1887-04-13
OIL AND GAS.

by Maurice Thompson State Geologist.l
The Trenton limestone, in which the oil and
gas of Indiana are found, belongs to group OF
rocks known as the Trenton formation, which
is part OF the lower Silurian deposits. It is a
marine rock, and in places is found to be
crowded with the shells, coral relics, erlnoid
stems. and other remains of sea life. LAM
plants probably did not exist in large number,
il at all, at the time this limestone was being
deposited, for the fossils of vegetable origin
found in the lower SIlurian rocks are chiefly
sea-weed remains. The Trenton rock, however
is often quite bituminous, especially in the
upperstrata, which sometimes contaia a great
deal of earbonaceous shsle.
The Trenton limestone does not outcr0p in
Indiana, unless there may be slight exposure
at some point in the extreme south
eastern limit on the Ohio. Tae
name is from Trenton Falls, on
West Canada Creek, in New York, where the
formation Is exposed in high bluffs. The
Birdseye limestone of the New York biologists
belongs to the Trenton formation. In some
places the limestones are almost black. From
Eastern Canada to Wisconsin, aud from New
York to Tennessee and farther south, the rocks
of the group, varying in Theological features,
are found in place. The Receptaculite lime
stone Of Missouri and the marbles OF East
Tennessee are referred to the Trenton,
The Trenton deposits are chiefly Limestone OF
a magnetism type. In Illinois they are reported
as being "brown magnetism limestone" In
Ohio they are brownish and grayIsh in color,
showing grsnulated and porous structure, the
substance efervescing ieebly, If at all, in d.
luted hydrochlorie acid. In Michigan the
limestone is, in places, agillaceous and OF blue
- I'll L ~N,l
color from buff to blue and IS magnetism.
In Pennsylvania it is often blue shale.
In Indiana, so far as may be made out from
the borings, it is a grayish or brownish lime
stone, sometimes highly magnetism. Under the
microscope it presents, usually, q granular,
porous, but exceedingly firm structure, with
traces OF something like wavy lines OF darker
color than the rest OF the substance. 1t is in
this limestone that our oil and gas are found,
and this limestone is one of the strata OF the
Trenton deposit or group. And would here say
that one not versed in geology will do well to
bear in mind that the Trenton limestone may
vary greatly in its character within the smallest
area, and that to "reaeh Trenton rock" is one
thing, and to reach the porous magnetism lime
stone OF the Trenton rock is quite another
thing What is limestone in one place, may, in
another place in the same geological horizon,
turn out to be shale, ana vice versa. Geological
horizon has nothing to do with a
reference to sea-level. Two places may
have very different sea-levels, and yet be on
the same geological horizon, or they may have
nearly the same altitude above the sea aud yet
have a great difference as to the geological
horizon. Lafayette and Kokomo may be less
than 100 feet apart in distance above the sea-
level and yet any OF the lower rocks may be
much deeper below one place than they are De-
| low the other. Therefore, when we speak OF
sealevel hereafter, let it be understood that it is
with reference to the altitude OF the Trenton
rock and not that OF the towns. In other words
| Union City, or Portland, or Marion may be
many feet higher above sea-level than Terre
| Haute, and yet, because of their lower geologi-
cal horizon, Trenton rock would be much nearer
the surface there than at Terre Hsute. OF
course this is well known to everybody who has
even a mere smattering OF geology, but 1t is
very hard for others to understand, hence the
| explanation.
THE UPPER SILURIAN AREA.
A straight line drawn from Indianapolis to
Richmond, Ind, will intersect the western
boundary Of the upper silurian area near the
northwestern corner of Washington Township,
in Rush County. Thence the area extends east
ward into Ohio, saving a small patch OF lower
| Silurian around Richmond. North of this east
and west line the upper Silurian area embraces
.most OF Henry and Wayne Counties, all OF Ran
dolph, Delaware, Jay, Blackford and Grant, aud
a large part Of Madison, Upton, Howard, Mi
ami, Wabash, Huntington, Wells and Adams
Counties. At present we need not consider the
southern area, as no gas has been found south
of Indianapolis though it may yet be found
| there.
The following is general section Of the chief
/ formations in Indiana